Collector ring bodies for electric motors

ABSTRACT

Collector ring bodies for encased high-speed electric motors, having a cylindrical hub of an insulating material, at least two non-metallic collector rings on the hub, and caps or sleeves for securing the rings to the hub, wherein either the hub or the securing elements, or both, are made from a material such as beryllium-oxide containing cements, thermosetting or thermoplastic materials, which provide good heat dissipation as well as electrical insulation.

United States Patent Fiirste et a1.

[451 Aug. 29, 1972 [54] COLLECTOR RING BODIES FOR ELECTRIC MOTORS [72]Inventors: Walter Fiirste Suhl Thuringin; Hans-Joachim Teuschler,Berlin; Joachim Schreiber, Berlin, all of Germany [73] Assignee: VVBElektrische Konsumguter, Berlin, Germany [22] Filed: Dec. 16, 1970 [21]Appl. No.: 98,755

[52] US. Cl. ..310/232 [51] Int. Cl. ..H01r 39/08 [58] Field of Search..310/232, 219, 223, 224, 233, 310/234, 235, 236, 238, 239

[56] References Cited UNITED STATES PATENTS 1,870,236 8/ 1932 Chervenka..310/232 3,091,714 5/1963 Jernberg ..310/232 1,991,057 2/ 1935McCloskey ..310/234 2,322,01 1 6/ 1943 French ..310/232 FOREIGN PATENTSOR APPLICATIONS 902,557 9/ 1 945 France ..310/232 932,810 9/1955 Germany..310/232 894,586 9/1953 Germany ..310/232 1,277,426 9/1958 Germany..310/232 Primary ExaminerJ. D. Miller Assistant Examiner-R. S. SkudyAtt0mey--Tab T. Thein [57] ABSTRACT Collector ring bodies for encasedhigh-speed electric motors, having a cylindrical hub of an insulatingmaterial, at least two non-metallic collector rings on the hub, and capsor sleeves for securing the rings to the hub, wherein either the hub orthe securing elements, or both, are made from a material such asberyllium-oxide containing cements, thermosetting or thermoplasticmaterials, which provide good heat dissipation as well as electricalinsulation.

13 Claims, 11 DrawingFigures P'A'TENTEDwsza I972 SHEET 1 BF 2 3INYENTORS LTER FORS WA TE HANS-J'OACHIM TEUSCHLER \TOACH M SCHREIBERCOLLECTOR RING BODIES FOR ELECTRIC MOTORS The invention relates tocollector ring bodies for high-speed electric motors of encasedconstruction and having collector rings made from non-metallicmaterials.

Collector ring bodies are well known for electric motors having rings ofnon-metallic materials, for example carbon. One kind of such bodies isconstructed by embedding their collector rings in cast resin. Suchembedded carbon collector rings may however be burst open during theoperation of the electric motor on account of the different expansioncoefficients of the two materials, whereby the entire collector ringbody is put out of service.

As a preventive measure the contact surfaces of the cast-resin body andof the carbon collector rings were provided with a coating that acts asa lubricant, which however can technically be realized only by usingprocedures that require considerable equipment.

Particularly when using collector ring bodies fitted with carbon ringsin encased motors, to be used for example in aggressive or noxiousatmospheres, difficulties are known to present themselves insofar as theheat of the collector rings, which is generated during the operation,and that can rise far beyond the admissible limit values, has to bedrawn away from the motors.

This is all the more important because the spark behavior and efficiencyof the entire collector ring body is endangered on account of thedifferent heat-expansion coefficients of the used materials. It has beenattempted in the past to solve this technical problem in various mannersand by different approaches.

Devices became known in which individual cylindrical support body partsare used between the body proper and the carbon collector rings, in lieuof a compact body, thereby completely to compensate the differentexpansion coefficients. The support body parts consist of cylindricalhub portions having bead-shaped projections symmetrically disposed abouttheir peripheries, the outer surfaces of the projections constitutingthe collector ring seats.

The number of the seats will correspond to that of the used currentconducting and tensioning bolts. Collector ring bodies of thisconstruction satisfy the requirements during the operation of theelectric motors and are particularly insensitive to the effects of thedifferent expansion coefficients of the two materials, owing to theirsmall share on contact surfaces between supporting body and carboncollector rings, but they require substantial technological expenditureduring the manufacturing process.

For the manufacture of the support body parts alone a complicated shapeis necessary. Different dimensions of the collector ring bodies anddifferent numbers of individual collector rings require differentlybuilt support body parts and shapes for their manufacture so that thesame remains uneconomical in spite of technological advantages.

There is also known a collector ring arrangement for high current loadswhere however surface ground contacts are used which are enclosed ontheir front surfaces, not bound by contacts, and on their outersurfaces, by an annular metal plate.A disadvantage in the use of sucharrangements is the required complete rebuilding of the electric motorsto which they are fitted.

It is an object of the invention, with respect to the inventivecollector ring bodies, to make use of the technical advantages achievedso far, and to reduce the technical requirements when making andapplying collector ring bodies with non-metallic collector rings,capable of withstanding substantial electric and thermal strains. I

It is another object of the invention to provide a collector ring bodyconstruction for high-speed encased electric motors, which provides forgood heat withdrawal with simultaneous compensation of the differentialexpansion conditions of the individual materials, and renders economicalthe manufacture of all required kinds and sizes of collector ring bodiesby making use of constructive expendients.

The objects are solved according to the most important features of thepresent invention by providing supporting or securing caps, sleeves orrings made of beryllium-oxide containing cements, thermosetting orthermoplastic materials, for heat dissipation on the front surfaces ofthe collector rings, the caps or rings touching the collector ringsalong surface areas, or being at least partly rigidly connectedtherewith. The caps or rings are in direct thermal contact with acylindrical support hub or boss which also consists of beryllium-oxidecontaining cements, therrnoor duoplastic materials.

The collector rings as well as the supporting caps or rings are receivedon the hub which has in its wall, starting from one side, axiallydisposed slots, or passages that terminate at the seating surfaces ofthe collector rings, at their envelopes, for receiving bandshapedconnecting elements which make electrical contact with the collectorrings.

In the case of collector ring bodies which are ex posed only to smallthermal stresses, it is sufficient to dispose the attached caps or ringsonly on the outer front surfaces of the collector rings which limit thecontact surfaces of the collector ring body while spacer rings orsleeves made of insulating material and engaging the carbon collectorrings are disposed between the individual rings, the sleeves thusadditionally protecting the collector rings against radial forces.

In accordance with the invention the supporting caps which limit thecollector ring body can also be provided with a cylindrical sleeve in acentral bore while a sleeve-shaped extension supplements the requiredlength of the entire support hub in the collector ring body. Suchextensions may also have passages or slots for receiving the band-shapedconnecting elements which contact the collector rings.

According to further features of the invention, for purposes of heatdissipation, spacing, mutual insulation and simultaneous protectionagainst centrifugal forces, the caps may be provided only on the outersurfaces of the collector rings, which surfaces limit the contact areasof the collector ring body, while insulating spacer rings or sleeves areconcentrically disposed between the collector rings, and rigidlyconnected therewith.

The band-shaped connecting elements or flags for current conduction aresecured to the inner peripheries of the collector rings by knowncontacting procedures; some of them may be axially bent or cranked so asto provide the required insulating distances, the connecting elementsprotruding from the body on one side of the assembly.

According to further features of the invention the support hub is madewith a beryllium-oxide containing cement, thermosetting or thermoplasticmaterial, preferably by centrifugal whirling action or casting, of theassembled unit including the collector rings, spacer rings or sleevesand caps. Carefully predetermined quantities of the centrifugallyapplied materials ensure the required bore, for receiving the usualarmature shaft.

For larger collector ring body measurements the invention provides acylindrical body to be inserted within the collector rings, therebyreducing the space or area that has to be filled by centrifuging.

For purposes of inner reinforcement, the entire collector ring bodyaccording to the invention can be impregnated with a binder, for examplea hardenable resin compound.

According to the invention, one or both of the concentric spacer ringsor sleeves can be provided in a perforated or air-permeable form foravoiding heat buildup.

Additionally, an electrically insulating, heat-conducting material canbe applied between the concentric spacers, preferably in the form of anorganically or inorganically bound beryllium-oxide material.

Collector ring bodies of the described kind can be produced economicallyand without difficulties, in all sizes and designs. Their constructionexcels in the bodies capacity to withstand considerable thermalstresses.

The intensive contact of the collector rings, where heat develops, bythe caps on the side surfaces, by the support hub in the central bore,as well as the excellent thermal contact between the caps and the hubproper, achieved by the particular construction, result in quick heatdissipation by way of the armature shaft, away from the encased motorhousing.

This effect is considerably enhanced by the application ofberyllium-oxide containing materials since they exhibit high heatconductivity as well as good insulating properties. By using simplecaps, rings and sleeves, as well as through the application of acentrifugal or casting process, the component parts of the inventivecollector ring bodies can be produced in a simple manner.

From the point of view of insulation the inventive construction ofiersconsiderable advantages since the band-shaped connecting elements arefully embedded in the insulating hub and/or the insulating centrifugedmaterials. Owing to the rigid connection between caps, spacer rings orsleeves and collector rings, centrifugal forces are substantiallycounteracted.

Other objects and many of the attendant advantages of the invention willbe readily appreciated as the same becomes better understood byreference to the following detailed description, when considered withthe accompanying drawings, wherein FIG. 1 is an end view of a firstexemplary embodiment of the inventive collector ring bodies;

FIG. 1a is a vertical section of the body shown in FIG. 1, taken alongline la la thereof;

FIG. 2 is a vertical section taken along line 2 2 of a second exemplaryembodiment shown in FIG. 2a;

FIG. 2a is a vertical section of the body shown in FIG. 2, taken alongline 2a 2a thereof;

FIG. 3 shows a different vertical section, along line 3 3 of a thirdexemplary embodiment shown in FIG. 3a;

FIG. 3a is a vertical section of the body shown in FIG. 3, taken alongline 3a 3a thereof;

FIG. 4 is a partial sectional view, similar to any of the precedingFIGS. 1a, 2a and 3a, of a modification;

FIG. 5 is an end view of a fourth exemplary embodiment of the inventivecollector ring bodies;

FIG. 5a is a vertical section of the body shown in FIG. 5, taken alongline 5a 5a thereof;

FIG. 6 is a side view of the body shown in FIGS. 5 and 5a; and

FIG. 7 is a vertical sectional modification of the fourth bodyembodiment.

In the following, various preferred, exemplary embodiments of theinventive collector ring bodies will be described, of which threeembodiments relate to threepart arrangements, that is with threecollector rings, while the fourth, as well as a modification thereof, isshown in a two-part arrangement, as will be explained in more detail.

The first embodiment is shown in FIGS. 1 and 1a, with threesubstantially coaxial collector rings 11 of a non-metallic material, forexample carbon, each being flanked on its sides by a pair of caps 12made, in accordance with the invention, from beryllium-oxide containingthermosetting or similar material. Peripheral collars of the caps 12cover respective portions on the contact surfaces of the enclosed rings11, as shown, while slightly protruding therebeyond.

Central bores of both rings 11 and caps 12 lodge a cylindrical supporthub or boss 13 which is preferably also made of a beryllium-oxidecontaining thermosetting material. The walls of hub 13 have, startingfrom one end, substantially axial passages therein, for receiving each aconnecting element or flag as shown at 14a, 14b, 140, respectively. FIG.1 shows that the passages are offset by and that the connecting elementsare, as a matter of example, in the form of bandshaped contact laminae.Each of them makes good electrical contact with one of the rings 11, attheir seats about the central hub 13, as shown in FIG. la for element14b.

The second illustrated embodiment (FIGS. 2 and 2a) is a collector ringbody which is not exposed to high thermal requirements, and thus it issufficient to use caps 12 only for flanking the outer surfaces or sidesof the two outermost rings 11 while between the latter, spacer rings 25are used, as shown in FIG. 2a. The arrangement of the passages insupport hub 13 and connecting elements 14a, 14b, 14c is substantiallythe same as in the first embodiment. It should be noted however thatelement 14a does not appear in FIG. 2 because it is a section takenbeyond (to the right-hand side) of the first ring 1 1 with which it isin electrical contact.

FIGS. 3 and 3a show a third exemplary embodiment with collector rings 11and caps 12 substantially as in FIGS. 1, la, but including a centralsleeve-shaped support hub 33 which incorporates, for example on itslefthand side, as shown, a projection similar to one of the caps, and onthe opposite, e.g. right-hand side, a sleeve extension 32. Connectingelements 14a, 14b, are again inserted in respective passages of thesupport hub, arranged at 120 each (when there are three collector ringsin the body). The connecting elements do not appear in FIG. 3 since itssection line falls beyond (to the right-hand side) of all three rings 11.

FIG. 4 constitutes a modification of the preceding embodiments insofaras collector rings 41 are each flanked by a pair of caps 42, the runningor contact surfaces of the former protruding somewhat beyond the outerperipheries of the latter, in contradistinction to the previousarrangements where it was the caps 12, spacer rings 25 and the hub andsleeve extension combination 32, 33 which protrude beyond the ringcontact surfaces.

It will be understood by those skilled in the art that not only theembodiment of FIGS. 1, 1a can be designed with cut-back rings 41 (inlieu of rings 11 shown therein), and somewhat shorter caps 42 (insteadof protruding caps 12), but the same arrangement can be used in thesecond and third embodiments disclosed herein, and the fourth to bediscussed hereinafter, considering that spacer rings 25, on the onehand, as well as support hub 33 and its sleeve extension 32, on theother, can also be made along the lines of the modification shown inFIG. 4, although not specifically illus trated.

In FIG. 2a, spacer elements 25 have been shown in the form of rings but,it should also be understood, they might be disk'shaped, similar to caps12, only with two lateral noses, which would be fully compatible withthe arrangement shown in FIGS. 2, 2a.

As mentioned before, the fourth embodiment, shown in FIGS. 5, 5a and 6,and a modification thereof in FIG. 7, illustrates an assembly with onlytwo circuits and associated collector rings although, it will beunderstood, a similar arrangement could be provided for three collectorrings (the same way as the previously described embodiments could alsobe used for another number of rings, other than three, as shown as amatter of exarnple).

The inventive fourth collector ring body includes collector rings 51 ofa non-metallic material, with caps 52 only on their outer sides, andhaving a support hub 53 provided between caps 52, as will be explainedsomewhat later in more detail. One of the caps 52 has passages oropenings 52a therein to accommodate respective connecting elements 54a,54b, each making electrical contact (e.g. by the application of anelectrically conductive adhesive) with the seat of one of the rings 51,as shown in FIG. 5a.

Concentrically disposed spacer rings or sleeves 55, 56, made from aninsulating material, immobilize rings 51 and assure a predetermineddistance therebetween. They preferably engage respective inner and outercircumferential recesses 51a in caps 51, which arrangement protects theassembly against centrifugal forces encountered during operation of themotors. Caps 52 hold rings 51 in an axial direction on account of theirsomewhat protruding noses, as shown.

The assembly of the fourth embodiment, including the described rings 51,caps 52, hub 53, spacer rings 55, 56 and the embedded connectingelements 54a, 54b, is produced by the centrifugal application or castingof a beryllium-oxide containing cement, thermosetting or thermoplasticmaterial, the desired inner diameter 53a of hub 53 being achieved by anappropriate dosage of the centrifuged materials, for the passage of anarmature shaft (not shown). The area to be filled with the materialsthat are whirled onto the assembly is delimited by the caps 52, theinner surfaces of the rings 51, and the inner spacer ring 56 whichengages the recesses provided on the inwardly facing peripherialportions of the two rings, as explained before.

From here on, modifications of the fourth embodiment will be described.For collector ring bodies of substantial diameters it is recommended,for example, to reduce the space to be centrifuged or cast, by theapplication of a sleeve-shaped body or insert 57 (see FIG. 7) which isindividually inserted in hub 53, as shown.

It has been found particularly advantageous, for removing or dissipatingheat from the rotating assembly, to use an electrically insulating,heat-conductive material or member 58, embedded between rings 51 andconcentric spacer rings 55, 56 (see FIG. 5a). Member 58 is preferablymade from an organically or inorganically bound beryllium-oxidematerial. It will be seen that FIG. 7 omits, as an alternative, the justdescribed insulating member 58, thus leaving an annular gap betweenspacer rings 55, 56.

While ring 56 (shown in both FIGS. 5a and 7) has a continuous,non-interrupted surface, outer ring 55, which limits the space to becentrifuged, can be provided with a perforated surface, to avoid heatbuildups, as shown in FIG. 6 (this detail being however omitted fromFIG. 5a, and from the modification of ring bodies of this invention maybe impregnated with or embedded in a binder or hardenable resin compound(not illustrated).

It should be understood, of course, that the foregoing disclosurerelates only to preferred, exemplary embodiments of the invention, andthat it is intended to cover all changes and modifications of theexamples described which do not constitute departures from the spiritand scope of the invention.

What we claim is:

l. A collector ring body for encased high-speed electric motors,comprising, in combination, substantially cylindrical insulating hubmeans, at least two nonmetallic collector rings disposed about said hubmeans, means for securing said rings and at least partly rigidtherewith, also disposed about said hub means, said rings haveperipheral grooves about at least one of their inner and outercircumferences, said grooves being engaged by at least one of saidspacers for protection against centrifugal forces and a hardenable resincompound in which the collector ring body is embedded for purposes ofinner reinforcement, wherein at least one of said hub means and saidsecuring means is made from a filling material selected from the groupconsisting of beryllium-oxide containing cements, thermosetting andthermoplastic materials, which provide good heat dissipation as well aselectrical insulation.

2. The collector ring body as defined in claim 1, wherein said hub meanshas substantially axial passages, for receiving therein electricalconnecting elements in a number corresponding to that of said rings.

3. The collector ring body as defined in claim 1, wherein said securingmeans includes a pair of caps flanking each of said rings.

4. The collector ring body as defined in claim 1, wherein said securingmeans includes at least one spacer element between a pair of said rings,said element having projecting peripheral portions for axiallyrestraining said pair of rings with respect to said hub means.

5. The collector ring body as defined in claim 1, wherein said hub meansincludes a sleeve-shaped hub and an extension at one end of said hub,while said securing means includes caps engaging the sides of some ofsaid rings, said sleeve-shaped hub and said extension having cap-shapedprojections which flank the outer sides of the outermost ones of saidrings.

6. The collector ring body as defined in claim 1, wherein said securingmeans includes caps engaging the sides of said rings, the contactsurfaces of the latter protruding somewhat beyond the outer peripheriesof said caps.

7. The collector ring body as defined in claim 1, wherein said securingmeans includes a pair of concentric spacers between a pair of saidrings, and a pair of caps flanking the outer sides of the outermost onesof said rings.

8. A collector ring body for encased high-speed electric motors,comprising, in combination,substantially cylindrical insulating hubmeans, at least two nonmetallic collector rings disposed about said hubmeans,

and means for securing said rings and at least partly rigid therewith,also disposed about said hub means, said securing means including a pairof concentric spacers between a pair of said rings, and a pair of capsflanking the outer sides of the outermost ones of said rings, whereinsaid rings have peripheral grooves about at least one of their inner andouter circumferences, said grooves being engaged by at least one of saidspacers for protection against centrifugal forces, and wherein at leastone of said hub means and said securing means is made from a fillingmaterial selected from the group consisting of beryllium-oxidecontaining cements, themiosetting and thermoplastic materials, whichprovide good heat dissipation as well as electrical insulation.

9. The collector ring body as defined in claim 7, wherein at least oneof said spacers has an air-permeable outer surface to avoid heatbuild-ups.

10. The collector ring body as defined in claim 7, further comprising anelectrically insulating, heat-conductive member inserted between saidspacers.

11. The collector ring body as defined in claim 10, wherein said memberis made from a beryllium-oxide material.

12. The collector ring body as defined in claim 7, wherein said fillingmaterial is cast in the space formed by said caps, the inner surfaces ofsaid rings and the inner one of said spacers.

13. The collector ring body as defined in claim 8,

wherein said filling material is cast in the space formed by said caps,the inner surfaces of said rings and the

2. The collector ring body as defined in claim 1, wherein said hub meanshas substantially axial passages, for receiving therein electricalconnecting elements in a number corresponding to that of said rings. 3.The collector ring body as defined in claim 1, wherein said securingmeans includes a pair of caps flanking each of said rings.
 4. Thecollector ring body as defined in claim 1, wherein said securing meansincludes at least one spacer element between a pair of said rings, saidelement having projecting peripheral portions for axially restrainingsaid pair of rings with respect to said hub means.
 5. The collector ringbody as defined in claim 1, wherein said hub means includes asleeve-shaped hub and an extension at one end of said hub, while saidsecuring means includes caps engaging the sides of some of said rings,said sleeve-shaped hub and said extension having cap-shaped projectionswhich flank the outer sides of the outermost ones of said rings.
 6. Thecollector ring body as defined in claim 1, wherein said securing meansincludes caps engaging the sides of said rings, the contact surfaces ofthe latter protruding somewhat beyond the outer peripheries of saidcaps.
 7. The collector ring body as defined in claim 1, wherein saidsecuring means includes a pair of concentric spacers between a pair ofsaid rings, and a pair of caps flanking the outer sides of the outermostones of said rings.
 8. A collector ring body for encased high-speedelectric motors, comprising, in combination, substantially cylindricalinsulating hub means, at least two non-metallic collector rings disposedabout said hub means, and means for securing said rings and at leastpartly rigid therewith, also disposed about said hub means, saidsecuring means including a pair of concentric spacers between a pair ofsaid rings, and a pair of caps flanking the outer sides of the outermostones of said rings, wherein said rings have peripheral grooves about atleast one of their inner and outer circumferences, said grooves beingengaged by at least one of said spacers for protection againstcentrifugal forces, and wherein at least one of said hub means and saidsecuring means is made from a filling material selected from the groupconsisting of beryllium-oxide containing cements, thermosetting andthermoplastic materials, which provide good heat dissipation as well aselectrical insulation.
 9. The collector ring body as defined in claim 7,wherein at least one of said spacers has an air-permeable outer surfaceto avoid heat build-ups.
 10. The collector ring body as defined in claim7, further comprising an electrically insulating, heat-conductive memberinserted between said spacers.
 11. The collector ring body as defined inclaim 10, wherein said member is made from a beryllium-oxide matErial.12. The collector ring body as defined in claim 7, wherein said fillingmaterial is cast in the space formed by said caps, the inner surfaces ofsaid rings and the inner one of said spacers.
 13. The collector ringbody as defined in claim 8, wherein said filling material is cast in thespace formed by said caps, the inner surfaces of said rings and theinner one of said spacers, and further comprising a sleeve-shaped insertapplied in the inner bore of said hub means.